The invention relates to polyacrylate esters with long-chain hydrocarbon and polyoxyalkylene groups, as well as to their use as surface active substances. In particular, the invention concerns polyacrylate esters with long-chain hydrocarbon and polyoxyalkylene groups with a reduced content of lower molecular weight components, as well as with a distribution of polymers which approximates the Poisson distribution. This distribution has the result that the compounds exhibit a low coefficient of non-uniformity M.sub.w /M.sub.n.
In another aspect, the invention relates to the use of such polyacrylate esters as surface active substances, in particular, as emulsifiers for the preparation of emulsions from natural and synthetic oils and water and especially the use of the aforementioned polyacrylate esters for the preparation of W/O emulsions of natural and synthetic oils.
Copolymers of polyoxyalkylene (meth)acrylates and alkyl (meth)acrylates are known from the art. In Japanese publication 61/145254, organic and inorganic pigments are disclosed, the surface of which is treated with a copolymer which consists of 1% to 99% by weight of polyoxyalkylene (meth)acrylate and 1 to 99% by weight of alkyl methacrylate, wherein the alkyl group of the alkyl methacrylate has 6 to 22 carbon atoms. These copolymers increase the dispersibility of pigments that are treated therewith.
German Offenlegungsschrift 3,636,429 discloses polymeric surfactants based on copolymers of hydrophobic and hydrophilic monomers which contain, in copolymerized form,
(a) as hydrophobic monomers, compounds of the formula ##STR1## in which R represents H or CH.sub.3
X represents C.sub.4 to C.sub.20 alkyl or ##STR2## R.sup.1 represents H, Cl to C.sub.20 alkyl, halogen or ##STR3## n is 1 to 4 R.sup.2, R.sup.3 represent H, C.sub.1 to C.sub.20 alkyl F, Cl, Br and PA1 Y is ##STR5## R.sup.4 represents H, CH.sub.3 or C.sub.2 H.sub.5 R.sup.5 represents H or C.sub.1 to C.sub.4 alkyl and PA1 m is 2 to 50. PA1 a1) saturated aliphatic alcohols with 4 to 22 carbon atoms, PA1 a2) unsaturated aliphatic alcohols with 8 to 22 carbon atoms, PA1 a3) alkyl phenols, the alkyl groups of which in each case have 8 to 12 carbon atoms or their oxyalkylation products with 1 to 4 oxyethylene and/or oxypropylene groups, and
(b) as hydrophilic monomers, compounds of the formula ##STR4## in which R represents H, CH.sub.3,
In aqueous systems, above the critical micelle concentration, these polymeric surfactants form micellar structures, which, in the case of a suitable structure and in particular concentration ranges, are present as liquid crystalline phases (mesophases). The copolymers disclosed in German Offenlegungsschrift 3,636,429 are said to make possible a wide variation of mesophasic structures and stability parameters. The copolymers have surfactant properties and the water soluble compounds can be used in detergent formulations to enhance detergency. The copolymers can also be used to increase the viscosity of aqueous phases, the viscosity increasing effect being largely independent of pH.
The compounds disclosed in German Offenlegungsschrift 36 36 429 are produced by copolymerization of the hydrophilic and hydrophobic monomers. These different monomers exhibit different polymerization parameters. This in turn causes the individual monomers to be not polymerized in homogeneous distribution to form a polymeric molecule. This can be demonstrated gelchromatagraphically by the existence of several peaks and a broad molecular weight distribution in the average polymer molecule. Gas chromatagraphically and by NMR spectroscopy, significant amounts of monomers and/or low-polymeric compounds can be demonstrated in the polymer. These moieties cannot be removed in economic manner from the mixture, since the boiling points of the monomeric compounds are too high for separation by distillation. Removal in other ways such, for example, by a selective extraction of the low molecular moieties is also not possible since the solubility behavior of the individual components is too similar and/or the compounds exhibit tensidic, to wit: surface active, properties which prevent the formation of separate layers between different immiscible solvents. This causes these compounds of the state of the art to exhibit a relatively high coefficient of non-uniformity.
However, for various reasons, these low molecular weight compounds are undesirable. The low molecular weight portions detract from and decrease the surface active properties of the known copolymers, since they themselves contribute little if anything to these properties. The low molecular weight portions are also undesirable for physiological reasons, since they can lead to health impairment, such as skin irritations, sensitization, etc.